The present invention relates to a circuit board testing fixture and, in particular, to a test fixture having support rails.
The use of a "bed of nails" test fixture has long been known for the testing of printed circuit boards. Such test fixtures include a plurality of metallic test probes arranged to make electrical contact between test points on the circuit board and a high speed electronic test analyzer. The electronic test analyzer has a standard grid of test points. The printed circuit boards to be tested are of varying sizes and the test points on the circuit board are varied from circuit board to circuit board. Therefore, the test fixture is customized for each circuit board pattern and includes a pattern of holes drilled to match the customized array of test points of the printed circuit board at a first plate and a standard grid of holes at a second plate corresponding to the standard grid of the electronic test analyzer. The probes mounted in the fixture in the drilled holes transfer the electrical test signals from the test analyzer to the circuit board in order to detect continuity or lack of continuity between various test points in the circuits on the board. Existing fixtures utilize rigid or resilient spacers to support and secure the various plates of the fixture together. Common fixtures have a top plate and a bottom plate and multiple intermediate plates residing therebetween. Vertical support members are placed periodically throughout the fixture in order to establish the total fixture height and position and support all intermediate plates and to maintain the spacing between the plates. These vertical support members are generally secured to the top and bottom plates with screws. In addition, each level of the fixture requires an individual support member at that level in order to support each plate at each level. Fixtures using such a support system may require at least one hundred pieces to provide the sufficient rigidity between all of the plates. Such an arrangement, having so many parts is costly. In addition, the assembly and disassembly time for such a fixture can be more than thirty minutes per fixture. Further, the additional drilling of holes in order to accommodate the screws of the support members requires additional time and labor, requiring an additional ten to fifty holes per fixture depending on the size of the fixture.
Therefore, it is an object of the present invention to provide a testing fixture which has a minimum number of pieces and is quickly and easily assembled while providing a rigid fixture to house test probes.
It is another object of the present invention to provide a testing fixture which includes a box-like configuration without the use of screws.
It is a further object of the present invention to provide a method of assembling a test fixture which is quickly and easily assembled.